Optical fibers are commonly employed for communicating data at high bandwidths. The investments to develop fiber optic communications technology have focused on making such bandwidths available over long distances. The long distances further necessitate producing cables that are simultaneously affordable and robust.
Fiber Optic cables typically must resist not only the traumas associated with transport and installation, but also the insidious effects of aging and long-term exposure to the elements, including environmental contaminants. One such example in a marine environment is referred to as the hydrogen darkening effect. Over a long exposure time, hydrogen, whether arising from corrosion, biological processes, or other marine-related causes, may diffuse into a core of an optical fiber and may react chemically with silicon, dopants, and/or other impurities to “tint” the optical signal-carrying material, such as glass. Over long distances the optical signal may be overwhelmed by the tint, resulting in excessive optical signal attenuation.
Permanent (hydrocarbon) reservoir monitoring (PRM) is a technique where multiple three-dimensional seismic “pictures” of the state of a hydrocarbon reservoir are taken such that a geologist or reservoir engineer may plan the location of additional boreholes for increasing the efficiency of the hydrocarbon extraction and/or may assess the efficiency of the current extraction techniques over time. In some cases, taking multiple seismic pictures of a hydrocarbon reservoir may be referred to as four-dimensional (4D) seismic.
Marine-based PRM faces significant challenges that are not faced by land-based reservoir monitoring systems. This is particularly true of ocean bottom installations as water depths extend into the 1000 meter range and beyond.